Packet processing in a multiple processor system

ABSTRACT

Packet processing is provided in a multiple processor system including a first processor to processing a packet and to create a tag associated with the packet. The tag includes information about the processing of the packet. A second processor receives the packet subsequent to the first processor and processes the packet using the tag information.

RELATED APPLICATIONS

This application claims priority under 35 U.S.C. §119(e) based on U.S.Provisional Patent Application Ser. No. 60/704,432 filed Aug. 2, 2005and is related to U.S. patent application Ser. No. 10/402,920, filed onMar. 28, 2003, which are herein incorporated by reference in theirentirety.

FIELD OF THE INVENTION

The principles of the invention relate generally to network packetprocessing systems and, more particularly, to packet processing inmultiple processor systems.

BACKGROUND

Network information can be split up into units of information calledpackets. Typically, the packets are routed dynamically between andwithin networks based on an efficient route between the source of thepacket and the destination of the packet. Each packet typically containsa header that includes source and destination information for routingthe packet and a data payload including typically a portion of theinformation being transmitted.

When a packet enters a network or system from an external source thepacket can be examined. The examination may include determining wherethe packet should be routed, but also can include processing the packetto evaluate possible threats posed by the packet to the network.Different packet processing devices can be used to examine packets, forexample, some packet processing devices target specific portions of apacket.

In a conventional network model, different packet processing devices canbe designed to examine different layers within a packet. For example, alayered network model called the Open Systems Interconnect (OSI) modelhas been created by the International Standards Organization (ISO). TheOSI model describes defined layers in a network operating system. Eachlayer has a defined input, output, and function. The OSI model defines aseven layer network and includes network and transport layers (layers 3and 4, respectively) and an application layer (layer 7).

One type of packet processing device is a firewall. A firewall can beused to secure a network from users outside the network. The firewallchecks, routes, and frequently labels all messages sent to or from usersoutside the network. Another packet processing device, such as anintrusion detection system, can be used to examine information beingcommunicated with a network to recognize suspicious patterns ofbehavior. Information obtained by the intrusion detection system can beused to block unauthorized or disruptive users from accessing thenetwork.

A flow-based router (FBR) allows network administrators to implementpacket forwarding and routing according to network policies defined by anetwork administrator. FBRs allow network administrators to implementpolicies that selectively cause packets to be routed through specificpaths in the network. FBRs can also be used to ensure that certain typesof packets receive differentiated, preferential service as they arerouted. Conventional routers can forward packets to their destinationaddress based on available routing information. Instead of routingsolely based on the destination address, FBRs enable a networkadministrator to implement routing policies to allow or deny packetsbased on several other criteria including the application, the protocol,the packet size and the identity of the end system.

A packet filter can operate on the packets in the network layer, todefend a trusted network from attack by an untrusted network. Packetfilters can operate at the network layer to inspect fields of theTransmission Control Protocol/Internet Protocol (TCP/IP) headerincluding, the protocol type, the source and destination InternetProtocol (IP) address, and the source and destination port numbers.

SUMMARY

The present specification describes systems and methods for providingpacket processing in a multiple processor system.

In one aspect consistent with the principles of the invention, a packetprocessing system is provided. The system includes a first processor forprocessing a packet and for creating a tag associated with the packet.The tag includes information about the processing of the packet. Thesystem includes a second processor to receive the packet subsequent tothe first processor. The second processor is configured to process thepacket using the tag information.

In a second aspect consistent with the principles of the invention, amethod for processing packets in a packet processing device is provided.The method includes receiving a packet at a packet processing device,directing the packet to a processor, processing the packet, creating atag associated with the packet, where the tag includes information aboutthe processing, forwarding the packet and the associated tag to a nextprocessor in the packet processing device, and processing the packet atthe next processor using the tag information.

In a third aspect consistent with the principles of the invention, theinvention provides a packet processing system. The system includes aflow engine to route a packet among a group of processors. The systemincludes a first processor of the group of processors to process thepacket and to create a tag to attach to the packet. The tag includesinformation about the processing of the packet by the first processor.The system includes a second processor of the group of processors toreceive the packet from the flow engine and to process the packetincluding using the tag information.

In a fourth aspect consistent with the principles of the invention, amethod for processing packets is provided. The method includes receivinga packet at a flow engine, routing the packet to a first processor,processing the packet at the first processor, creating and attaching atag to the packet at the first processor, where the tag includesinformation about the processing useful to a next processor,transmitting the packet, including the tag, to the flow engine, routingthe packet, including the tag, to the next processor, and processing thepacket at the next processor using the tag information.

Implementations of the systems may include one or more of the followingfeatures. One processor of the system can be a firewall. One processorof the system can be an intrusion detection system. The tag can beappended or prepended to the packet. The tag includes data processed bythe second processor. The tag information can include sessioninformation, flow information, instructions for inspection of thepacket, an indication to drop the packet, or an indication to dropsubsequent packets from a same session as the packet. Flows and sessionsare described in U.S. patent application Ser. No. 10/072,683, filed Feb.8, 2002, entitled “Multi-Method Gateway-Based Network Security Systemsand Methods,” the contents of which are incorporated herein by referencein its entirety.

The details of one or more embodiments of the invention are set forth inthe accompanying drawings and the description below. Other features andadvantages of the invention will become apparent from the description,the drawings, and the claims.

DESCRIPTION OF DRAWINGS

FIG. 1 shows an exemplary network topology including a processingsystem.

FIG. 2 a illustrates a block diagram of an exemplary processing systemincluding multiple tag generators.

FIG. 2 b illustrates a block diagram of an alternative processing systemincluding a single tag generator.

FIG. 3 a illustrates a block diagram of an alternative processing systemincluding serial processors.

FIG. 3 b illustrates a block diagram of an alternative processingsystem.

FIG. 4 illustrates an exemplary packet processing engine and a taggenerator.

FIG. 5 illustrates a second exemplary packet processing engine and a taggenerator.

FIG. 6 is a flowchart describing the operation of an exemplaryprocessing system including a flow engine.

FIG. 7 is a flowchart describing the operation of an exemplaryprocessing system including serial processors.

FIG. 8 illustrates a block diagram of an exemplary processing systemincluding a firewall and an intrusion detection system.

FIG. 9 is a flowchart describing the operation of an exemplaryprocessing system including a firewall and an intrusion detectionsystem.

Like reference numbers and designations in the various drawings indicatelike elements.

DETAILED DESCRIPTION

FIG. 1 illustrates a network topology including a local area network(LAN) 100, including a server 102, several workstations (W/S) 104 a-104c (collectively, “104”), and a processing system 124. Processing system124 may include a group of processing engines 106 a-106 d (collectively,“106”) for processing packets. LAN 100 may be connected to an externalnetwork e.g., the Internet 114 b, through processing system 124. LAN 100may also be connected to a second LAN 116 through a router 118, andsatellite 120. Second LAN 116 may include a web server 110, an emailserver 112, a server 102, several workstations 134 a-113 f(collectively, “134”) and a processing system 126. LAN 116 may beconnected to the Internet 114 a via processing system 126. Processingsystem 126 may include processing engines 128 a-128 b (collectively,“128”). The computers, servers and other devices in the LAN may beinterconnected using a number of data transmission media such as wire,fiber optics, and radio waves. Processing system 124 and processingsystem 126 may operate in a similar manner. Using processing system 124by way of example, processing engines 106 may include a firewallprocessing engine, an intrusion detection system, a network addresstranslation (NAT) engine and other processing engines. Processingengines 106 can act in conjunction with each other to facilitate theefficient processing of packets at different network levels. Forexample, a firewall processing engine can examine packet information atnetwork layer 3 and layer 4 levels while an intrusion detection enginecan look at a different network layer in the packet, such as networklayer 7 information. The firewall processing engine may provideinformation regarding results of the firewall's processing to theintrusion detection engine in order to facilitate processing by theintrusion detection engine. The communication between processing enginesis discussed in greater detail below.

FIG. 2 a illustrates an implementation of a processing system, such asprocessing system 124 a. Processing system 124 a may include a packetinterface 210 for receiving packets, a flow engine 220, such as aflow-based router, a group of processing engines 230 a-230 c(collectively, “230”), and a group of tag generators 240 a-240 c(collectively, “240”). Packet interface 210 may transmit receivedpackets to flow engine 220, which may route the packets to processingengines 230. Processing engines 230 may process individual packets basedon some predetermined criteria. For example, processing engine 230 canbe a firewall processing engine that examines packets at network layer 3and layer 4. Processing engines 230 may be coupled to tag generators240. Tag generators 240 can be used to attach tags to packets followingprocessing by processing engines 230. Tag generators 240 can replaceexisting tags attached to packets with new tags. Tag generators 240 canalso attach new tags to packets without altering or removing an existingtag or tags. Packets can thus have multiple attached tags.Alternatively, tag generators 240 can be used to modify an existing tagattached to packets. The tag content is described in further detail withrespect to FIG. 4 below. Three processing engines 230 a, 230 b, and 230c are illustrated in FIG. 2 a coupled parallel to each other through theflow engine 220. Any number of processing engines 230 can, however, beincluded in the processing system 124 a.

FIG. 2 b illustrates an alternative implementation of processing system124 a. Processing system 124 a may include packet interface 210 forreceiving packets, flow engine 220, such as a flow-based router, aplurality of processing engines 230 a-230 c (collectively, “230”), and ashared tag generator 250. Packet interface 210 may transmit receivedpackets to flow engine 220, which may route the packets to processingengines 230. Processing engines 230 may process individual packets basedon some predetermined criteria. For example, processing engine 230 canbe a firewall processing engine that examines packets at the networklayer 3 and layer 4. Processing engines 230 may be coupled to shared taggenerator 250. Shared tag generator 250 can be used to attach tags topackets following processing by processing engines 230. Attached tagscan replace existing tags or tags can be attached without modifying anyexisting tags. Alternatively, shared tag generator 250 can be used tomodify an existing tag attached to packets. In one implementation, allprocessing engines 230 share one tag generator. In anotherimplementation, a subset of processing engines 230 share one of a groupof shared tag generators.

FIG. 3 a illustrates an alternative implementation of processing system124 a. Processing system 124 a may include an incoming packet interface310 for receiving packets into processing system 124. Received packetsmay pass though interface 310 to first serial processing engine 320 a.First serial processing engine 320 a may be coupled to a first taggenerator 330 a for attaching tags to packets after processing. Firstserial processing engine 320 a may be coupled serially to second serialprocessing engine 320 b. Second serial processing engine 320 b may becoupled to second tag generator 330 b. Additional serial processingengines can be coupled in series from second serial processing engine320 b. Additional tag generators can be coupled to each additionalserial processing engine. Tag generators 330 a and 330 b (collectively,“330”) can generate a new tag or can modify an existing tag. New ormodified tags can replace existing tags or can be attached withoutreplacing existing tags. Tags may be sent over paths 350 a and 350 b(collectively, “350”) and packets may be sent over paths 305 a and 305 b(collectively, “305”). Alternatively, packets and tags may be sent overa common path. FIG. 3 a illustrates processing system 124 a having threeserial processing engines 320 a. Any number of processing engines 320,however, can be included in processing system 124 a. Interface 340 maybe coupled to a last serial processing engine, in this case third serialprocessing engine 320 c, through which packets exit processing system124 a.

Other packet processing architectures can be implemented, such asprocessing system 124 a illustrated in FIG. 3 b. FIG. 3 b shows analternative arrangement of processing engines and tag generators.Processing engine 370 can receive a packet from processing engines 360a-360 c (collectively, “360”) and tag generators 365 a-365 b(collectively, “365”). Each of the processing engines 360 may receivepackets from a source, such as an interface or another processing engine(not shown). Processing engines 360 may then process packets and taggenerators 365 may attach a tag to each of the packets. The packets maythen be transmitted to processing engine 370. Processing engine 370 iscoupled to tag generator 375 for creating a new tag or for modifying anexisting tag after processing by processing engine 370. New or modifiedtags can be attached to a packet without impacting an existing tag, or anew or modified tag can replace an existing tag. After processing byprocessing engine 370, packets can be transmitted to one or moreadditional processing engines 380 a-380 c (collectively, “380”).Processing engines 380 may be coupled to tag generators 385 a-385 c(collectively, “385”) for attaching a tag to the packets. The packetsmay then be transmitted to other devices, such as processing engines forfurther processing of the packet or an interface for transmissionoutside of processing system 124 a.

FIG. 4 illustrates a portion of the path of packet 460 in processingsystem 124 as illustrated in FIG. 2 a. FIG. 5 illustrates a portion ofthe path of a packet in processing system 124 as illustrated in FIG. 3a. Referring now to FIG. 4, packet 460 is routed by a flow engine 420from an interface (not shown) to a first processor 410. First processor410 may include a processing engine 430 and a tag generator 440. Afterprocessing, processing engine 430 may transmit a packet, which mayinclude a header and a data payload, to tag generator 440. Tag generator440 may attach a tag to the packet and may transmit the packet/tagcombination back to flow engine 420 for routing to a next processor 450.

Tag generator 440 may generate tags based on the results of theprocessing by first processing engine 430. The tags can includeinformation useful to next processor 450 in processing the associatedpacket. Additionally, tags can include information or instructions forflow engine 420. Tags can include information from all prior processingsteps. or can include only the processing of the immediately precedingprocessing engine. The tag information can include, but is not limitedto, some or all of the following: network layer 3 and layer 4 data, acontext pointer, a cookie, a next processing context, and acommunication action flag. In a network having a seven layer model,network layer 3 and layer 4 information includes information such assource IP address, destination IP address, protocol, port numbers, TCPstates, running sequence numbers, and retries. The context pointerprovides context information for the packet that can be useful for thenext processing engine. For example, the context pointer can includesession information for the packet. The session information informs theprocessing engine of the session the packet belongs to, can provide forconsistent treatment of all packets within a particular session, andprovide for expedited processing of subsequent packets belonging to asame session.

A cookie can be included that provides a composite of system-relatedinformation for the processing of a specific packet. For example, apacket subject to special inspection, resulting from a user policyconfiguration, can include a cookie with information about the specialinspection required for use by the subsequent processing engines. Thenext processing context information can instruct a subsequent processingengine on actions to take following processing of the packet. The tagcan also include information on which processing engine should processthe packet next or can include instructions for a subsequent processingengine. For example, a firewall processing engine can attach a tagfollowing processing that directs the intrusion detection engine totransmit the packet to a particular processing engine followingprocessing by the intrusion detection engine. In a further example, theintrusion detection engine can be instructed to transmit the packet nextto a Virtual Private Network (VPN) processing engine for encryptionfollowing intrusion detection. In one implementation, the nextprocessing context may include both a processing engine ID, identifyingthe desired processing engine the instructions are directed to, as wellas context information for the processing engine. The contextinformation being provided to a VPN processing engine can include, forexample, a security association for the packet. A security associationcan include, for example, the unique encryption keys for a session sothat the VPN processing engine knows which encryption key to use on thepacket and all packets in the same session.

The communication action flag can be generated to provide communicationbetween different processing engines and between processing engines anda flow engine. For example, a communication action flag attached to apacket by a processing engine can inform the flow engine not to routeany more packets from the same session to any processing engines. Forexample, if the intrusion detection engine determines that a packet ispart of an attack, the intrusion detection engine can attach a tag tothe packet instructing the flow engine to drop all incoming packets fromthe session upon receipt. The communication action flag can also includean indication for a processing engine or a flow engine to otherwiseprocess the packet. Otherwise processing can include dropping, logging,alarming, and holding the packet.

Referring now to FIG. 5, a packet may be routed by an interface 520 to afirst serial processor 510. First serial processor 510 may include afirst serial processing engine 530 and a tag generator 540. The packetmay include a header and a data payload, and may be transmitted fromfirst serial processing engine 530 to tag generator 540. Tag generator540 may attach a tag to the packet and may transmit a packet/tagcombination to a second serial processor 550. Tag generator 540 maygenerate the tag based on the results of the processing by first serialprocessing engine 530. The tag can include information useful to secondserial processor 550 in processing the packet. The tag information caninclude, but is not limited to, some or all of the following: networklayer 3 and layer 4 data, a context pointer, a cookie, a next processingcontext, and a communication action flag. The content and use of the tagattached to the packet may be similar to the tag content and usedescribed above with respect to FIG. 4.

FIG. 6 provides a flowchart illustrating operations performed byprocessing system 124 a of FIG. 2 a. A packet is received by flow engine220 from interface 210 (step 610). Flow engine 220 may route thereceived packet to first of processing engines 230 (step 620). Theprocessing engine processes the packet (step 630). Processing can takenumerous different forms depending on the type of processing engine. Forexample, a processing engine performing firewall processes can examinelayer 3 and layer 4 information within a packet to search for a networkattack.

After processing the packet, a determination may be made as to whetheror not to continue processing the packet (step 640). For example, if theprocessing engine is a firewall, processing can determine that thepacket is part of an attack. As a result, the processing engine canotherwise process (e.g., drop, log, alarm, or hold) the packet (step650). If the processing is to continue, a tag may be attached to thepacket by the tag generator associated with the processing engine (step660). For example, if the packet is suspected of an attack based on theanalysis by a firewall processing engine, the tag can includeinstructions for a subsequent one of processing engines 230 (forexample, an intrusion detection engine) to make a careful investigationof the packet to determine whether or not the packet is an attack, andto drop the packet if it is an attack. In an alternative implementation,instead of dropping the attack packet, a tag may be attached to thepacket that includes a communication action flag for flow engine 220.The communication action flag may instruct flow engine 220 to drop thepacket and any received packets matching the session of the packet.Conversely, if the packet is determined by the firewall processingengine to be a packet that is not suspect, the tag can includeinformation informing the intrusion detection engine that no detailedinvestigation is necessary. The tag can also include instructions forone of processing engines 230 or flow engine 220 to “otherwise process”the packet. “Otherwise processing” the packet can include, for example,dropping, logging, alarming, holding, and alerting, each of which mayresult in the content of the packet being modified.

The packet with the attached tag may be transmitted back to flow engine220 for routing to subsequent processing engine 230 (step 670), as shownin FIG. 4. Flow engine 220 may then determine if more processing engines230 are used to process the packet prior to routing the packet to adestination outside processing system 124 a (step 680). Flow engine 220can use information in the tag to determine what further processing isrequired. If no other processing engines 230 are to process the packet,flow engine 220 may route the packet through interface 210 to thedestination (step 695). If other processing engines 230 are to processthe packet, flow engine 220 may route the packet to the next ofprocessing engines 230 to process the packet (step 685). Additionally,flow engine 220 can receive instructions within the tag from one ofprocessing engines 230. For example, if the firewall processing enginedetermines that a packet is part of an attack, a tag including acommunication action flag can be sent to flow engine 220 informing flowengine 220 not to route any more packets from the same session as thepacket.

A next one of processing engines 230 may then process the packet usinginformation obtained from the attached tag (step 690). The next one ofprocessing engine 230 may examine the tag for information based onprevious processing of the packet. The tag can provide informationleading to expedited or more intensive processing by the next one ofprocessing engines 230. For example, the tag can provide informationindicating that a previous one of processing engines 230 determined thatthe packet was possibly part of an attack and requires detailedexamination by a next one of processing engines 230. Alternatively, thetag can provide information indicating that a previous one of processingengines 230 determined that the packet was not a threat and does notrequire detailed examination by a subsequent one of processing engines230.

After processing, flow may return to step 640 to determine if processingof the packet should continue. For example, the packet can be cleared bythe firewall processing engine only to be recognized by the intrusiondetection engine as part of an attack. Upon discovery of the attack, theintrusion detection engine can determine that no further packets fromthe attack session should be processed. If the processing is terminated,the packet can be otherwise processed, for example by dropping thepacket (step 650). If the processing is allowed to continue, a new tagmay be attached to the packet reflecting the processing (step 660). Thenew tag can be attached to the packet by a tag generator for aparticular one of processing engines 230, or the new tag can be attachedto the packet by a shared tag generator 250 (FIG. 2 b). Alternatively,new data may be attached to the old tag instead of attaching a new tagto the packet.

In another implementation, a packet to be dropped can have a tagattached including instructions to flow engine 220 not to route anyfurther packets from the session of the packet. The process from step640 to step 690 may be repeated for each of processing engines 230 untilno other processing engines 230 are to process the packet. For example,flow engine 220 can determine, based on prior processing steps and taginformation, if further processing is required. When no other processingengines 230 are to process the packet, flow engine 220 may route thepacket to the destination (step 695). In one implementation, the tag maybe discarded by flow engine 230 before routing the packet outsideprocessing system 124 a.

FIG. 7 shows a flowchart illustrating processing system 124 a of FIG. 3a. Processing system 124 a may receive a packet at interface 310 (step710). Interface 310 may transmit the packet to first serial processingengine 320 a (step 715). First serial processing engine 320 a mayprocess the packet (step 720). As described above with respect to FIG.6, processing can include examination of different network layers withinthe packet. First serial processing engine 320 a can be a firewall asdiscussed above with respect to FIG. 6, or some other processing engine.After processing, first serial processing engine 320 a may determine ifthe packet should be transmitted to a next one of serial processingengines 320 (e.g., second serial processing engine 320 b) for furtherprocessing (step 725).

If first serial processing engine 320 a determines that the packetshould not be processed further, the packet may be otherwise processed(step 730). If first serial processing engine 320 a determines that thepacket can continue processing, a tag may be attached to the packet bytag generator 330 (step 735). If there are more serial processingengines 320 (step 740) then the packet may be transmitted to next ofserial processing engines 320 (e.g., second serial processing engine 320b) (step 745). The next one of serial processing engines 320 may thenprocess the packet using the tag information contained in the tag (step750). After the next one of serial processing engines 320 processes thepacket using the tag information, the flow may return to step 725 for adetermination of whether or not to continue processing the packet. Ifthe packet is not to be processed further, the packet may be otherwiseprocessed (step 730). If the processing is to continue, a new tag may beattached to the packet by one of tag generators 330 (step 735). In analternative implementation, new data may be attached to an existing tag.The tag information can include information from all prior processingsteps or can include only the processing of the immediately precedingone of processing engines 320. The tag can also include instructions forprocessing engines 320 to otherwise process the packet. Otherwiseprocessing the packet can include dropping, logging, alarming, andholding. The tag information can include the same information asdescribed above with respect to FIG. 4.

The flow from step 725 to step 750 continues for each subsequent one ofserial processing engines 320 (e.g., third serial processing engine 320c) until no further serial processing engines 320 remain to process thepacket. The last of serial processing engines 320 (e.g., third serialprocessing engine 320 c in FIG. 3) may transmit the packet to thedestination as defined, for example, by the destination IP address ofthe packet (step 755). In one implementation, a tag may be removed bylast serial processing engine 320 before transmission of the packet tointerface 340. In another implementation, the tag may be removed byinterface 340 prior to transmission of the packet to the destination.

FIG. 8 illustrates a processing system 800 that may include an incominginterface 810 that receives a packet from an external source, such as anexternal network. Incoming interface 810 may route the packet to afirewall 820 for processing. Firewall 820 includes a tag generator 830for attaching a tag to a packet. A packet/tag combination can betransmitted from firewall 820 to an IDS 840 for further processing.After processing, the packet can be transmitted to an outgoing interface850. Outgoing interface 850 may then route the packet out of processingsystem 800 to the packet's destination.

FIG. 9 shows a flowchart illustrating exemplary processing of processingsystem 800 of FIG. 8. Processing system 800 may receive a packet atinterface 810 (step 910). Interface 810 may transmit the packet tofirewall 820 (step 915). Firewall 820 may process the packet (step 920).The processing by firewall 820 may include examination of the packet atnetwork layer 3 and layer 4. Processing by firewall 820 may also includeperforming a session look-up on the packet in order to determine towhich session the packet belongs. Based on the examination, firewall 820may determine whether to transmit the packet to the next processor (step925). If examination by firewall 820 reveals that the packet is athreat, the packet can be otherwise processed (e.g., dropped) (step930). If the packet is allowed to proceed, tag generator 830 maygenerate and attach a tag to the packet (step 935). The tag may includesession ID information for the packet as determined by firewall 820. Thetag can also include log information for the packet.

The firewall may then transmit a packet/tag combination to IDS 840 forprocessing (step 940). IDS 840 may use the session ID contained withinthe tag so that the IDS does not have to perform a session look-up onthe packet. As a result, IDS 840 can apply policies on how to processthe packet based on the session ID without performing a session lookup(step 945). After processing, IDS 840 may determine whether or not thepacket is allowed to proceed out of processing system 800 (step 950).If, based on the processing, the packet is not allowed to proceed, thepacket can be otherwise processed (e.g., dropped) (step 955). If thepacket is allowed to proceed, the tag may be removed and the packet maybe routed through interface 850 to the packet's destination (step 960).

Tags can be appended or prepended to the packet. A new tag can begenerated with each processing or the tag can have new data appended orprepended to the existing tag. The tag can include instructions as wellas data to be processed by the processing engines or by the flowengines.

In one implementation, a tag generator can be used to attach a tag priorto a determination of continued processing. A tag can be automaticallygenerated following processing by a processing engine and then adetermination can be made as to whether or not the processing shouldcontinue, or the packet with tag can be forwarded to another device fora determination of continued processing. In another implementation, theprocessing engines may include a tag analyzer for analyzing the taginformation in order to determine what level of processing is requiredfor the packet.

In one implementation, each tag generator and processing engine pair canbe integrated on one printed circuit board (“PCB”) or alternatively onone integrated circuit (“IC”). In another implementation, multiple pairsof processors and tag generators can be integrated on one PCB or on oneIC. In a further implementation, a plurality of processing engines canshare the same tag generator. Additionally, in an implementationincluding a flow engine, the flow engine can be integrated with aplurality of processing engines on one PCB or on one IC. Further, theflow engine can be integrated with a plurality of processing engines andat least one tag generator on one PCB or one IC.

The invention and all of the functional operations described herein canbe implemented in digital electronic circuitry, or in computer hardware,firmware, software, or in combinations of them. The invention can beimplemented as a computer program product, i.e., a computer programtangibly embodied in an information carrier, e.g., in a machine-readablestorage device or in a propagated signal, for execution by, or tocontrol the operation of, data processing apparatus, e.g., aprogrammable processor, a computer, or multiple computers. A computerprogram can be written in any form of programming language, includingcompiled or interpreted languages, and it can be deployed in any form,including as a stand-alone program or as a module, component,subroutine, or other unit suitable for use in a computing environment. Acomputer program can be deployed to be executed on one computer or onmultiple computers at one site or distributed across multiple sites andinterconnected by a communication network.

Method steps of the invention can be performed by one or moreprogrammable processors executing a computer program to performfunctions of the invention by operating on input data and generatingoutput. Method steps can also be performed by, and apparatus of theinvention can be implemented as, special purpose logic circuitry, e.g.,an FPGA (field programmable gate array) or an ASIC (application-specificintegrated circuit).

Processors suitable for the execution of a computer program include, byway of example, both general and special purpose microprocessors, andany one or more processors of any kind of digital computer. Generally, aprocessor will receive instructions and data from a read-only memory ora random access memory or both. The essential elements of a computer area processor for executing instructions and one or more memory devicesfor storing instructions and data. Generally, a computer will alsoinclude, or be operatively coupled to receive data from or transfer datato, or both, one or more mass storage devices for storing data, e.g.,magnetic, magneto-optical disks, or optical disks. Information carrierssuitable for embodying computer program instructions and data includeall forms of non-volatile memory, including by way of examplesemiconductor memory devices, e.g., EPROM, EEPROM, and flash memorydevices; magnetic disks, e.g., internal hard disks or removable disks;magneto-optical disks; and CD-ROM and DVD-ROM disks. The processor andthe memory can be supplemented by, or incorporated in special purposelogic circuitry.

To provide for interaction with a user, the invention can be implementedon a computer having a display device, e.g., a CRT (cathode ray tube) orLCD (liquid crystal display) monitor, for displaying information to theuser and a keyboard and a pointing device, e.g., a mouse or a trackball,by which the user can provide input to the computer. Other kinds ofdevices can be used to provide for interaction with a user as well; forexample, feedback provided to the user can be any form of sensoryfeedback, e.g., visual feedback, auditory feedback, or tactile feedback;and input from the user can be received in any form, including acoustic,speech, or tactile input.

The invention can be implemented in a computing system that includes aback-end component, e.g., as a data server, or that includes amiddleware component, e.g., an application server, or that includes afront-end component, e.g., a client computer having a graphical userinterface or a Web browser through which a user can interact with animplementation of the invention, or any combination of such back-end,middleware, or front-end components. The components of the system can beinterconnected by any form or medium of digital data communication,e.g., a communication network. Examples of communication networksinclude a local area network (“LAN”) and a wide area network (“WAN”),e.g., the Internet.

The computing system can include clients and servers. A client andserver are generally remote from each other and typically interactthrough a communication network. The relationship of client and serverarises by virtue of computer programs running on the respectivecomputers and having a client-server relationship to each other.

A number of implementations of the invention have been described.Nevertheless, it will be understood that various modifications may bemade without departing from the spirit and scope of the invention.Accordingly, other implementations are within the scope of the followingclaims.

1. A packet processing system, comprising: a first processor to processa packet and to create a tag associated with the packet, the tagincluding information about the processing of the packet; and a secondprocessor to receive the packet subsequent to the first processor, andconfigured to process the packet using the tag information.
 2. Thepacket processing system of claim 1, wherein one of the first processorand the second processor is included in a firewall.
 3. The packetprocessing system of claim 1, wherein one of the first processor and thesecond processor is included in an intrusion detection system.
 4. Thepacket processing system of claim 1, wherein the tag is appended to thepacket.
 5. The packet processing system of claim 1, wherein the tag isprepended to the packet.
 6. The packet processing system of claim 1,wherein the tag includes data processed by the second processor.
 7. Thepacket processing system of claim 1, wherein the tag includes anindication to drop subsequent packets from a same session as the packet.8. The packet processing system of claim 1, wherein the tag informationincludes at least one of session information, flow information,inspection instructions, or drop indications.
 9. The packet processingsystem of claim 1, wherein the second processor is further configured tocreate a new tag associated with the packet, the tag includinginformation about the processing of the packet.
 10. The packetprocessing system of claim 1, wherein the second processor is furtherconfigured to add new data to an existing tag.
 11. The packet processingsystem of claim 1, wherein each of the processor includes a taggenerator to create tags.
 12. The packet processing system of claim 1,wherein the processors are configured to share a tag generator to createtags.
 13. The packet processing system of claim 1, wherein a pluralityof the processors and at least one tag generator are integrated on oneprinted circuit board.
 14. The packet processing system of claim 1,wherein a plurality of the processors and at least one tag generator areintegrated on one integrated circuit.
 15. The packet processing systemof claim 1, wherein a plurality of the processors are included on oneprinted circuit board.
 16. The packet processing system of claim 1,wherein a plurality of the processors are included on one integratedcircuit.
 17. A method for processing packets in a packet processingdevice, comprising: receiving a packet at a packet processing device;directing the packet to a processor; processing the packet; creating atag associated with the packet, the tag including information about theprocessing; forwarding the packet, and the associated tag, to a nextprocessor in the packet processing device; and processing the packet atthe next processor using the tag information.
 18. The method of claim17, further comprising: otherwise processing a packet based on theprocessing by a processor.
 19. The method of claim 18, wherein theotherwise processing of the packet includes at least one of dropping,logging, alarming, or holding.
 20. The method of claim 17, wherein oneprocessor is included in a firewall. 21-42. (canceled)